HU185210B - Thermoplast coatins and process for producing these coating - Google Patents

Abstract

The present invention relates to thermosetting two-component coating compositions containing (A) a prepolymer having an average molecular weight of from 1,000 to 15,000 having an average of from 2 to 4 ketoxime-blocked aromatic isocyanate groups; (B) a crosslinking agent corresponding to the following general formula: <IMAGE> wherein R1, R2, R3 and R4 independently represent hydrogen or C1- to C3-alkyl groups with the proviso that if R1 to R4 all are hydrogen, 75% of the diamine have the cis,cis-structure and optionally (C) pigments, fillers blowing agents or other known additives. The equivalent ratio of blocked isocyanate groups to NH2 groups is from about 1.35:1 to about 0.95:1, and the coating composition contains not more than about 15% by weight of organic solvents and is free from aqueous polymer dispersions or solutions. The coating compositions may be applied to substrates by the direct or reverse process and may be applied as a top coat, adhesive coat or foam coat.

Description

The present invention relates to a process for the preparation of a thermosetting, anhydrous polyurelane-based layering agent from a ketoxime protected prepolymer containing aromatic NCO groups and a crosslinking agent. The coating agent

(A) from prepolymerates having an average molecular weight of 1000 to 1500 containing on average 2-4 ketoxime protected aromatic NCO groups,

B) from 4,4'-diamino-3,3'-dimethyldicyclohexylmethane of formula I as a crosslinking agent, wherein the equivalent ratio of protected NCO groups to NH ₂ groups is 1.35: 1 and 0. , 95: 1 - prepared and optionally

C) pigments, fillers, propellants, and known additives

The coating agent contains a total of up to 15% by weight of organic solvent.

German Patent Publication No. 28 14 079 discloses a film-forming agent comprising an aqueous polymer dispersion or polymer solution.

Coating textiles with polyurethane urea solutions where the solvent content can reach up to 70% is already known. Not only fully reacted polyurethane ureas are used for this purpose, but also polyurethane ureas which contain an additional component and are subsequently cross-linked. The latter solution improves the quality of the coating applied. Coating agents of this type are described in U.S. Patent 3,711,571. Dissolved polyurethane ureas are mixed with oxime protected NCO-doped polymerizates and the resulting coating is cured in a drying tunnel by heat treatment. The disadvantage of this coating application is that it requires the use of at least 50% solvent (in which case the solvent used to form the protecting group is not mentioned).

Other solvent-free polyurethane urea based coatings are described in U.S. Patent No. 3,755,261 and in U.S. Patent No. 2,462,317. There is disclosed a thermosetting mixture consisting of a liquid NCO prepolymerizate and a curing agent containing 4,4-diaminodiphenylmethane salt (MDA). The starch agent is made liquid by suspending the MDA-salt complex with at least 50% by weight of a phthalic acid ester-type plasticizer. According to the embodiments, the NCO pre-polymerizers have a relatively high free diisocyanate content.

However, this type of coating agent exhibits physiological disadvantages. The relatively high amount of free diisocyanate, but especially the MDA used as a starch, has an unfavorable toxicity. A further disadvantage is that the blossoming or sweating of these types of coatings does not allow them to provide a dry, flawless topcoat. British Patent No. 970,459 discloses a method of bonding foam film to a fabric. They use a reactive mixture as an adhesive, which is a ketoxime protected NCO prepolymerizate and a crosslinker.

NN, ^N, N'4etrakisz-2- (hydroxy-propyl) - ·· ethylenediaminetetraacetate as a crosslinking agent. Because this system is cured through the urethane groups and not the urea groups, they eventually produce soft films that are not suitable for forming topcoats.

Verhanig, J. (Proceedings of the Leather Industry Congress, October 18-22, 78, Budapest, pages 1279-1288, OMKDK Technoinform 1428; Budapest), reports a PUR system free of thermoactive solvent where it is protected by a polyether-based NCO- blends of prepolymers with polyetheramines having a molecular weight of about 750 can form foam coatings. Apart from the toxic effects of phenol cleavage, this system has the disadvantage that due to its mechanical properties it can only be used in a very narrow application area.

SUMMARY OF THE INVENTION The object of the present invention is to overcome the known drawbacks and to provide a solvent-free or solvent-poor physiologically harmless coating agent which meets the requirements of the application and is suitable for the production of foam, adhesive, coating layers or even weldable coatings.

The coating agents prepared according to the invention fulfill this purpose.

The composition obtained by the process of the invention is used to coat various materials.

The ketoxime-protected NCO prepolymers are prepared from aromatic polyisocyanates as disclosed in U.S. Patent No. 3,984,607, and in U.S. Patent No. 4,035,213, and U.S. Patent Publication No. 2457387. The present invention preferably comprises 2,4'- and 4.4'-diisocyanate diphenylmethane, isomeric toluene diisocyanate and a mixture of these diisocyanates.

For the preparation of the NCO prepolymerizate, the reaction partners of these polyisocyanates are phthydroxyl compounds having 2 to 8, preferably 2 to 3 hydroxyl groups, and having a molecular weight of 500 to 10,000, preferably 1000 to 6,000, as disclosed in the aforementioned publications.

The present invention preferably employs an average of 2 to 3 hydroxy group propylene oxide polyethers which may also contain polyethylene oxide units or a hydroxyl polyester having a molecular weight of 1000 to 6000 having a 2- or 3-terminal hydroxyl group melting below 60 ° C.

In particular, the hydroxy-polyether and hydroxy-polyester mixtures which are formed from adipic acid, hexanediol-1,6-b, are preferably used in the present invention. and are formed from neopentyl glycol having an average molecular weight of 1000-3000.

Low molecular weight polyols having a molecular weight of less than 300, which are known per se as chain extenders, may also be considered in the preparation of NCO prepolymerizations. Among these compounds, it is expedient for the present invention

Butanediol-1,4 and trimethylol-propane are used.

The NCO prepolymerizates can be prepared in a known manner by reacting said polyhydroxyl compounds with an excess of diisocyanate, conveniently at a temperature of about 70-120 ° C. In the reaction, the NCO-OH ratio is generally 1.5: 1-6.0: 1, preferably 1.7: 1-2.5: 1.

NCO-prepolymerizates include protecting groups such as ketoximes and ketones of hydroxyamine, such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, acetophenone and benzophenone.

Methyl ethyl ketoxime (butanone oxime) is conveniently used in the present invention to form a protecting group.

The deprotection is carried out by stoichiometric amounts of ketoxime in the NCO prepolymer. at elevated temperatures, such as 70-100 ° C, until the NCO groups disappear.

The protected NCO prepolymerizates are mixed with up to 15% by weight, preferably 10% by weight, of organic solvent to adjust the optimum viscosity for the protected NCO prepolymerization. The optimum processing viscosity is 20-40,000 mPas at 20 ° C. Since the NCO groups contain a protecting group, it is not necessary to use a solvent which is inert to the NCO groups. Suitable solvents include, but are not limited to, isopropanol, ethylene glycol monomethyl, ethylene glycol monoethyl ether, and acetic acid esters of these compounds, methyl ethyl ketone, cyclohexanone, butyl acetate, or dimethylformamide.

For the NCO prepolymer protected group, the preferred crosslinking agent according to the present invention is 4,4'-diamino-3,3-dimethyldicyclohexylmethane, a low vapor pressure aliphatic diamine which is liquid at room temperature.

The NCO prepolymerizate having a protecting group is mixed with the diamine crosslinking agent in an equivalent weight ratio, although in some applications it is preferable not to fully crosslink the protected NCO to the NH ₂ group. generally 1.35: 1 and 0.95: 1, preferably 1.25: 1 and 1; 1.

Additives known per se, such as pigments, UV stabilizer, antioxidant, filler, blowing agent, may be added to the reactive compositions of the present invention. In practice, the thermosetting reactive mixtures can be applied directly or by the reverse coating process. Depending on the specific chemical structure of the NCO prepolymer, layers of various properties such as adhesive, foam or coating may be applied.

In the reverse process, according to the invention! in this embodiment, the reactive mixture is first applied to an intermediate support layer, such as a release paper, in an amount of about 30 to 100 g / mm ² ; then curing the layer in a drying tunnel; about 30-100 g / mm ² of the reactive mixture is again applied as the adhesive to the dry coating layer, and the desired material is laminated thereto by treatment in an additional drying tunnel at about 120-190 ° C, preferably 140-175 ° C. curing at temperature, then peeling off the coated layer from the release paper. Of course, the operation can also be carried out by preparing the coating and adhesive layer alone and using known coating systems for the other coatings.

Reactive mixtures as mentioned above can also be applied to textile layers for direct coating. The solvent-free or solvent-poor coating agent of the present invention is preferred over thick coating agents. The application of the agent according to the invention in an amount of 100-200 g / mm ² may result in 0.4 mm thick technical coatings, which require a few operations steps.

If the coating agent of the present invention is to be used to produce a foam layer, heat-release compounds are used as the propellant; in addition, foam stabilizers may conveniently be used. Suitable additives are described in German Patent Publication No. 1794006 (British Patent No. 1,211,339) and U.S. Patent No. 3,262,805.

In prior art PUR reactive systems, generally only intermediate layers such as adhesive or foam layers could be prepared. In the case of coating, either not enough surface was obtained or physiologically problematic starting materials were used. According to the state of the art, it was not expected that the reactive mixture according to the invention could be used to coat textile materials. Surprisingly, it has been found that the present invention is also suitable for forming coating layers and that the mechanical properties obtained are comparable to those obtained with PUR solutions. The advantage of the process according to the invention over the prior art is that the starting materials used are physiologically acceptable according to the state of the art. The following examples illustrate the invention.

Preparation of NCOeol Polymerate with Protective Group

A) prepolymerizate

4,000 g of 6,000 molecular weight propylene oxide and trimethylpropane based hydroxypolyether and 275 g 550 molecular weight bisphenol A and propylene oxide based hydroxypolyether with 375 g of 4,4-diisocyanate diphenylmethane and 261 g of 2,4-diisocyanate toluene at 80-90 ° C. until the calculated NCO content drops below just 2.56% by weight. Subsequently, 261 butanone oxime was added at 60-70 ° C. After approximately 20 minutes, the presence of NCO is no longer detectable by infrared spectroscopy. Protected NCO prepolymerizate

-3185 2 IC is a clear, colorless liquid having a viscosity of 50,000 mPas at 20 ° C. The resulting material had a latent NCO content of 2.34% by weight, thus having an NCO equivalent of 1800.

B) prepolymerizate

2000 g of 6000 molecular weight trimethylpropane and propylene oxide based polyether, 1000 g of 1000 molecular weight propylene glycol and propylene oxide based linear polyether, 1450 g of 1200 molecular weight hexanediol 1.6 neopentyl glycol and adipic acid linear polyester and 22.5 g of butanediol 1,425 g of 4,4-diisocyanate-diphenylmethane and 174 g of 2,4-diisocyanate-toluene were reacted at 8 ° C to 90 ° C for about 3 hours until the NCO content dropped to just under 4.6% by weight. 496 g of butanone oxime and 696 g of ethylene glycol monomethyl ether acetate were then rapidly added at 60-70 ° C. After 20 minutes, no NCO group can be detected by infrared spectroscopy. The NCO prepolymer protected thus obtained is a colorless, clear liquid having a viscosity at 10 ° C of about 40,000 mPas and a latent NCO content of about 3.3% by weight, i.e., an NCO equivalent weight of 1280.

C) prepolymerizate

2000 g of 1700 molecular weight hexanediol-1.6 neopentyl glycol and adipic acid-based hydroxyl polyester were reacted with 358 g of 2,4-d.isocyanate toluene at 80-90 ° C until the NCO content was 4.25% by weight. decrease. 174 g of butanone oxime and 250 g of ethylene glycol monomethyl ether acetate are rapidly mixed at 70 'C with this prepolymerizate. After approximately 20 minutes, the presence of NCO groups was no longer detectable by infrared spectroscopy. The protected prepolymerizate is a colorless, clear liquid having a viscosity of about 40,000 mPas at 20 ° C and a latent NCO content of 3.5% by weight, i.e. an NCO equivalent of 1200%.

Example I

The present example describes the preparation of a coating on a textile material consisting of a cotton layer, an adhesive layer and a coating layer, the process being carried out by the reverse solution.

The paste used for the adhesive layer contains 1800 g of prepolymer A and 119 g (i.e. equimolar amount) of 4,4'-diamino-3,3'-dimethyldicyclohexyl) methane. The paste has a viscosity of about 30,000 mPas at room temperature and remains unchanged for at least two weeks.

The coating paste used contains 1280 g of prepolymer B and 119 g (i.e. equimolar amount) of 4,4'-diamino-3,3'-dimethyldicyclohexyl) methane. In addition, the coating layer paste contains 10% by weight of a commercially available pigment powder, 0.2% by weight of silicone oil and 2% by weight of silicate filler. The viscosity of the usable paste at room temperature is about 40,000 mPas.

Applying the above coating layer paste to a coating apparatus capable of applying two coats with a cylindrical paint smoothing knife; the application rate is 70 g / mm ² , and the paste is applied to blotting paper. The coating is cured in a drying tunnel for 2 minutes at 140-160 ° C. As the second layer, as described above, the adhesive layer paste described above is applied in an amount of 60 g / mm ² . The paste is applied to the hardened coating layer. Subsequently, a curled cotton textile layer is applied by carding. The adhesive layer is cured in the second drying tunnel at 140-160 ° C for 2-3 minutes.

The coating is dry and soft to the touch: hardness of the surface is 80 Shore A. The coating has good chemical resistance, hydrolysis resistance and impact resistance.

Example 2

Manufacture of textile coverings. In this process, a cotton textile material is provided with an adhesive, foam and coating layer, by the reverse process.

The adhesive or coating paste has the same composition as the pastes described in Example I.

The composition of the paste for the foam layer is 1280 g of prepolymer B and 119 g (i.e. equimolar amount) of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane. In addition, the paste contains 15% by weight of diphenyl-3,3'-disulfone hydrazide as a propellant, as well as 0.2% by weight of silicone oil and 7% by weight of silicate filler. The viscosity of the ready-to-use paste is 4000 mPas at room temperature.

The apparatus described in Example 1 is used, a

The coating layer paste is applied to the release paper at 60 g / mm ² on Layer ² and then held in a drying tunnel at 140-150 ° C for 1-3 minutes (depending on tunnel efficiency and nozzle size). The coating layer thus crosslinked is coated with a release paper, and the coating layer is then applied again to the release paper. The foam layer in layer 1 is prepared by applying an amount of 180 g / mm ² to the coating layer, heat-drying it in a drying tunnel at 140-160 ° C, first foaming with gas, and then curing. In the application layer 2, the adhesive paste is applied at 60 g / mm ² ; apply this layer to the foam layer. Then the textile material (non-fluffy cotton) is laced. The layers thus obtained are cross-linked again in the drying tunnel and passed through a cooling roller; then peel off the wrapping paper and wrap it. The resulting layer is dry and soft to the touch; Even after aging at 90 ° C, the strength of the layers is satisfactory.

-4185ζίϋ

Example 3

Direct welding of a thick weldable flat coating.

The adhesive paste is prepared as follows: To 1200 g of prepolymer B is added 102 g of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane; the reactive components have an NCO / NH ₂ ratio of 1.25. In addition, the paste contains 2% by weight of silicate filler, 0.5% by weight of silicone oil and 10% by weight of PVC plastisol.

The coating paste contains 1200 g of prepolymer C and 119 g (i.e. equimolar) of 4,4'-diamino-3,3'-dimethyldicyclohexymethane. In addition, 10% by weight of ground pigment powder and 2% by weight of silicone oil are added to the paste. The viscosity of the usable paste at room temperature is 40,000 mPas.

In the film forming apparatus referred to in Examples 1 and 2, 100 g / mm ^{2 of the} above adhesive film paste is applied to a textile web of the first roll. The web is made of polyester. The applied layer is then cured at a temperature of 140-160 ° C in a drying tunnel. In the second pass, a 200 g / mm ² topcoat forming paste is applied to this adhesive layer and cured in the second drying tunnel as described above.

If necessary, the coatings described herein may be applied to the back of the textile web.

As a result, a flat sheet having a thickness of about 0.3 mm is obtained, which has favorable properties, is resistant to light and weather. The plane coating produced is resistant to mechanical impact. The coated flat profile can be welded thermally or by high frequency welding.

Claims (6)

Patent claims CLAIMS 1. A process for the preparation of a thermosetting anhydrous polyurethane based layering agent from a prepolymer and a crosslinking agent containing ketoxime protected aromatic NCO groups. A) aro ⁵ prepolymerizates having an average molecular weight of 1000-1500 and containing 2-4 ketoxime groups on average, and B) of formula (I) of 4,4'-diamino-3,3'-dimethyl-diciklchexil chloride as crosslinking agent on mixing in an amount such that the ratio of the protective groups ¹⁰ in Ella NCO groups to NH ₂ groups of 1, 35: 1 to 0.95: 1 and optionally mixed C) pigments, fillers, blowing agent, known additives, and up to 15% by weight of solvent is ¹⁵ to gouge. 2. The process of claim 1 wherein component A is a prepolymerizate having an average molecular weight of 2000-8000. Process according to claims 1 and 2, characterized in that a prepolymer consisting of diphenylmethane diisocyanate and / or toluene diisocyanate is used. 4. Process according to any one of claims 1 to 3, characterized in that a prepolymer is formed of a polyester having 2-3 free hydroxyl groups of 500-10000 molecular weight and / or 2-3000 hydroxyl groups having a free weight of 1000-6000 molecular weight. The method of claim 4, wherein 30 having 2-3 free hydroxy groups A prepolymerization of propylene oxide polyester having a molecular weight of 1000-6000, optionally containing ethylene oxide units and / or an adipic acid polyester having 2-3 free hydroxy groups. 6. A process according to any one of claims 1 to 3, wherein the NCO group is a methyl ethyl ketoxime protected prepolymer.